Saliva is an important biological matrix that allows the investigation of various welfare parameters; in ruminants, it is abundant and can be easily collected without requiring professional veterinary intervention. The aim of the investigation was to provide additional information on both digestive and antioxidant enzymes of sheep farmed in good welfare conditions, assessed with the Animal welfare indicators (AWIN) protocol. Small surgical forceps holding a Salivette® device (Sarstedt, Nümbrecht, Germany) were gently inserted into the sheep’s mouths without any force. The sheep chewed the swabs independently for a few seconds, allowing saliva collection. Seventeen enzymes from the saliva of 15 sheep were analyzed: antioxidant enzymes (catalase, glutathione S transferase), proteolytic enzymes (trypsin, chymotrypsin, N-aminopeptidases, carboxypeptidase A and B), carbohydrases (glucose oxidase, amylase, cellulase, lignin peroxidase, chitinase and α-glycosidase), and esterases (alkaline and acidic phosphatases, lipase and esterase). Esterase activity showed the highest value (12.95 ± 1.25 U/mg of proteins), whereas lignin peroxidase activity showed the lowest (2.23 ± 0.37 µU/mg of proteins). The activity of all enzymes was observed except for glutathione S transferase and α-glycosidase. Among the enzymes, lipase activity has already been identified as a biomarker of stress in sheep saliva. This investigation may represent a basis for further investigations into the diet and adaptive responses of sheep to different environmental conditions. Furthermore, samples collected using the Salivette® device can be easily obtained without requiring specialized staff and without causing any stress to the animals. Further investigations into the origin of individual enzymes using a proteomic approach are desirable.

BackgroundBipolar disorder (BD) is a chronic mental illness displaying recurrent episodes of impaired mood, in alternance with euthymic or subsyndromal periods. The comorbidity between BD and post-traumatic stress disorder (PTSD) is attracting attention due to its frequency, diagnostic difficulties, and worsening prognosis. Consequently, identifying molecular substrates of post-traumatic vs. depressive symptoms in BD would provide much benefit for patients’ rescue. This study thus focused on tryptophan (TRP) metabolism, at the crossroad between neurotransmission, immunity and inflammation, under distinct BD mental conditions.MethodsWe compared plasma TRP, serotonin (5-HT), kynurenine (KYN) and quinolinic acid (QUIN) among 20 euthymic-BD patients with PTSD (PTSD group) or 20 with depressive episode (DEP group) and 24 controls (CTL group). Metabolic ratios were calculated to monitor TRP-path fluxes. All participants underwent clinical examinations by psychometric instruments as the: Structured Clinical Interview for DSM-5 disorders (SCID-5), Hamilton Depression Rating Scale (HAM-D), Young Mania Rating Scale (YMRS), Impact of Event Scale-Revised (IES-R), Mood Spectrum-Self-Report lifetime version (MOODS-SR), Trauma and Loss Spectrum-Self Report lifetime version (TALS-SR), Work and Social Adjustment Scale (WSAS). Blood withdraws were also achieved, followed by plasma measurements through ELISA.ResultsBoth DEP and PTSD-groups revealed markedly lower 5-HT and 5-HT/TRP values than controls, with additionally decreased 5-HT in DEP- vs. PTSD-subjects. DEP-patients also showed reduced TRP and increased QUIN, KYN and QUIN ratios vs controls, while PTSD-subjects displaying only increased QUIN/KYN values. Additionally, several correlations between biochemical and clinical parameters were reported. Noteworthy, 5-HT and 5-HT/TRP were negatively correlated with all psychometric measures, while all biochemical parameters studied, except KYN, were correlated with poor socio-personal functioning; otherwise, KYN-shunt parameters better distinguished the severity of DEP symptoms than the PTSD ones.ConclusionsSubstantially, BD-patients with low 5-HT and severe burden could be distinguished based on KYN profiles/trajectories when affected by depression or PTSD, entailing different neuroinflammatory/neuroendocrine patterns in mood vs. post-traumatic stress dimensions. This will encourage deeper assessment of BD metabolic/inflammatory biomarkers, allowing for refined patients’ stratifications and targeted therapeutic interventions.

Neuroendocrine and circadian dysfunctions are thought to underlie bipolar disorder (BD) and could be implemented as markers of complex symptom conditions, including the presence of Post-Traumatic Stress Disorder (PTSD) comorbidity. The primary objective of this study was to investigate neuroendocrine profiles in different BD phenotypes through the measure of nocturnal urinary levels of Cortisol (stress-response factor) and 6-sulfatoxymelatonin (aMT6s; light/dark signal) in euthymic BD patients diagnosed with PTSD (PTSD group) or with major depressive episodes without trauma symptoms (DEP group). Both groups were compared against healthy controls (CTL). Nighttime urinary levels of aMT6s and Cortisol were analyzed by competitive ELISA, with ensuing values normalized for specific gravity. The Cortisol-to-aMT6s ratio (Cort/aMT6s) was calculated as an exploratory proxy for the homeostatic balance between HPA-mediated catabolic/coping activities and Melatonin-related reparative functions. Clinical severity and psychosocial activities were assessed by using mood HAM-D, YMRS, trauma IES-R and functioning WSAS scales. Results revealed distinct biological patterns: PTSD subjects showed increased nocturnal Cortisol compared to DEP and CTL groups, whereas DEP patients exhibited lower aMT6s levels and an elevated Cort/aMT6s ratio. Cortisol and aMT6s correlated positively in PTSD, while the ratio correlated positively with Cortisol solely in controls. Clinically, Cortisol correlated positively with IES-R and functional impairment (WSAS), whereas aMT6s correlated negatively with HAM-D and YMRS scores. Present findings suggest a possible neuroendocrine divergence in BD patients with depression versus PTSD: nocturnal Melatonin deficiency may be associated with depression, while HPA-axis hyperactivity and altered crosstalk between the two systems may characterize PTSD comorbidity, with the Cort/aMT6s ratio as a potential index of impaired daily functioning. These results could be promising for the use of biomarkers linked to allostatic and circadian responses within the BD spectrum.

OBJECTIVES:The study aimed to investigate whether involvement in a stable romantic partnership is associated with differences in peripheral brain-derived neurotrophic factor (BDNF) levels. METHODS:In a cross-sectional study, 60 healthy adults (32 women; mean age 27.4 ± 4.1 years) were classified as in a stable relationship (n = 31) or not (n = 29) after a clinical interview. Morning fasting blood was collected to quantify serum and platelet BDNF using a mature-BDNF sandwich ELISA. Data were analysed with t-tests and two-way ANOVA (group, sex), reporting effect sizes. RESULTS:Participants in a relationship showed higher PLT-BDNF (4.36 ± 1.22 vs 2.85 ± 0.67 ng/mg; t(58) = 5.90, p < 0.001, d = 1.52) and higher serum BDNF (36.83 ± 6.95 vs 25.47 ± 5.23 ng/ml; t(58) = 7.12, p < 0.001, d = 1.84) than participants without a current stable romantic relationship. Two-way ANOVA confirmed a main effect of group for PLT-BDNF (F = 35.35, p < 0.001, η2 = 0.39) and serum BDNF (F ≈ 50, p < 0.001, η2≈0.47), while the sex and group × sex interactions were not statistically significant for both PLT-BDNF and serum BDNF. CONCLUSIONS:Our results would indicate that a stable romantic partnership is associated with higher intraplatelet and serum BDNF levels. These findings support an association between current committed romantic relationship status and peripheral BDNF measures in healthy adults.

BACKGROUND AND AIMS:Recent translational and clinical research emphasise the concept of interacting neurochemical disruptions as a ground for the development of psychosis. At the same time, literature highlighted neurostructural and functional alterations in ASD. However, evidence linking biochemical markers to psychotic symptoms in the context of ASD is still scarce. In this perspective, we aim to investigate biochemical correlations and predictive biological factors of psychotic symptoms in autism, also considering gender differences. METHODS:For this study, we recruited a total of 22 ASD adult patients assessed through the Psychotic Spectrum - Self-Report version (PSY-SR). Furthermore, a blood sample was drawn in order to perform biochemical evaluations. All biochemical parameters were detected with an ELISA kit. RESULTS:considering gender differences, male patients showed higher micromolar HCy levels.Spearman correlation analyses revealed significant correlations between PSY total and single domains and biochemical correlates such as TRP metabolites, plasmic 5-HT and BDNF. Finally, linear regression analyses, revealed specific patterns of negative and positive biochemical predictors (particularly those with the kynurenine pathway) for psychotic symptoms in ASD. CONCLUSIONS:Globally, our work highlighted that, in ASD adults, psychotic symptoms may be associated with specific biochemical alterations, in particular linked to the kynurenine pathway, BDNF and 5-HT.

Prolonged Grief Disorder (PGD) is marked by enduring and disruptive grief symptoms following the death of a significant other. Although PGD has been recognized as a distinct psychopathological entity within the trauma dimension in the DSM-5-TR, its neurobiological underpinnings remain not fully defined. A systematic literature review was conducted up to September 2025 following PRISMA 2020 guidelines. PubMed, Scopus, Embase and Web of Science were searched using a comprehensive strategy combining MeSH terms and free-text keywords. Eligible studies included human participants, validated grief assessment tools and biomarker assessments. Out of 2140 initial records, 12 studies published between 1989 and 2022 met inclusion criteria. Investigated neuro–psycho–endocrine systems included the hypothalamic–pituitary–adrenal (HPA) axis, catecholamines, oxytocin, endocannabinoids and immune/inflammatory markers. Key findings in pathological grief reactions included altered cortisol rhythms, elevated oxytocin levels, increased pro-inflammatory cytokines and immune system dysregulation. Results are limited by heterogeneity in study designs, small sample sizes, inconsistent use of diagnostic criteria prior to DSM-5-TR and lack of control for psychiatric comorbidities. This review highlights emerging biological correlates of PGD, particularly those involving the stress response, reward-attachment networks and immune/inflammatory pathways. Further standardized, longitudinal research is essential to gain a more defined picture of PGD, to clarify causal mechanisms and to guide targeted therapeutic interventions.

Introduction Patients with Post-traumatic stress disorder (PTSD) or mood disorders, as depression, often showed dysregulation of the hypothalamic-pituitary-adrenal axis and autonomic nervous system, resulting in increased levels of pro-inflammatory cytokines and heightened activity of the immune system that may cause alterations in the structure and function of brain regions through direct neurotoxic effects, oxidative stress, changes in levels of neurotransmitters and decreasing some neurotrophins. Among the most studied pro-inflammatory cytokines in this field there are Intereleukine-6 (IL-6) and Interleukine-1β (IL-1β); however, scant and conflicting data are currently available in the literature about their use as potential biomarkers, and even less on possible comparisons in PTSD and depression. Objectives The aim of the present study was to evaluate circulating levels of IL-6 and IL-1β in patients with PTSD and to compare them with those of subjects with depression and healthy controls. Methods A sample of 45 subjects, including 15 subjects diagnosed with PTSD (PTSD group), 15 with depression (DEP group), and 15 healthy controls (HC group) were recruited at the Psychiatric Clinic of the Department of Clinical and Experimental Medicine, University of Pisa. HC group included subjects recruited on a voluntary basis. The psychiatric diagnosis was assessed by the Structured Clinical Interview for DSM-5-Clinician Version (SCID-5-CV), the Impact of Event Scale-Revised (IES-R) and the Trauma and Loss Spectrum-Self Report lifetime version (TALS-SR). A peripheral venous blood sample was collected to perform the biochemical assays. The analyses of IL-6 and IL-1β were performed with a dedicated enzyme-linked immunosorbent assay (ELISAs) achieved at the Laboratory of Biochemistry of the Department of Pharmacy, University of Pisa. Results No statistically significant gender or age differences emerged in the three groups. There were no statistically significant differences in IL-1β levels among the three groups. Conversely, the PTSD group showed higher levels of IL-6 compared to the DEP and to the HC ones, with a statistically significant difference in the post-hoc analysis among the PTSD and DEP groups with respect to the HC one (p<0.05). Conclusions Our results suggest the key role of a chronic low-grade inflammatory state in PTSD and in depression, probably related to a dysregulation in HPA axis and cortisol release, with an increase in proinflammatory cytokines including IL-6 that seemed to be more pronounced in PTSD. Disclosure of Interest None Declared

Post-traumatic stress disorder (PTSD) is a highly disabling mental disorder arising after traumatism exposure, often revealing critical and complex courses when comorbidity with bipolar disorder (BD) occurs. To search for PTSD or depression biomarkers that would help clinicians define BD presentations, this study aimed at preliminarily evaluating circulating brain-derived-neurotrophic factor (BDNF) levels in BD subjects with PTSD or experiencing a major depressive episode versus controls. Two bloodstream BDNF components were specifically investigated, the storage (intraplatelet) and the released (plasma) ones, both as adaptogenic/repair signals during neuroendocrine stress response dynamics. Bipolar patients with PTSD (n = 20) or in a major depressive episode (n = 20) were rigorously recruited together with unrelated healthy controls (n = 24) and subsequently examined by psychiatric questionnaires and blood samplings. Platelet-poor plasma (PPP) and intraplatelet (PLT) BDNF were measured by ELISA assays. The results showed markedly higher intraplatelet vs. plasma BDNF, confirming platelets’ role in neurotrophin transport/storage. No between-group PPP-BDNF difference was reported, whereas PLT-BDNF was significantly reduced in depressed BD patients. PLT-BDNF negatively correlated with mood scores but not with PTSD items like PPP-BDNF, which instead displayed opposite correlation trends with depression and manic severity. Present findings highlight PLT-BDNF as more reliable at detecting depression than PTSD in BD, encouraging further study into BDNF variability contextually with immune-inflammatory parameters in wider cohorts of differentially symptomatic bipolar patients.

To date, although several studies have investigated the circulating levels of brain-derived neurotrophic factor (BDNF) in children with autism spectrum disorder (ASD), only a few authors have addressed their evaluation in adults. Furthermore, an important limitation of these studies lies in the fact that circulating BDNF is stored in platelets and released into the circulation when needed. To the best of our knowledge, a very limited number of studies have related peripheral BDNF values to platelet counts, and yet no study has evaluated intra-platelet BDNF levels in adults with ASD. In this framework, the aim of the present work is to pave the way in this field and evaluate platelet BNDF levels in adult ASD patients, as well as their correlation with autistic symptoms and related psychopathological dimensions. We recruited 22 ASD and 22 healthy controls, evaluated with the Adult autism subthreshold spectrum (AdAS Spectrum), the Social Anxiety Spectrum—self report (SHY-SR), the Trauma and loss spectrum—self report (TALS-SR), the Work and Social Adjustment Scale (WSAS), and the Mood Spectrum—self report for suicidality. Intra-platelet BDNF levels were also assessed. The results highlighted lower BDNF levels in the ASD group; moreover, AdAS Spectrum and WSAS total score as well as AdAS Spectrum Restricted interest and rumination, WSAS Private leisure activities, TALS-SR Arousal, and SHY-SR Childhood domains were significant negative predictors of platelet BDNF levels.

Honeybees (Apis mellifera L.) have to face many challenges, including Varroa destructor infestation, associated with viral transmission. Oxalic acid is one of the most common treatments against Varroa. Little is known about the physiological effects of oxalic acid, especially those on honeybees’ immune systems. In this study, the short-term effects (0–96 h) of oxalic acid treatment on the immune system components (i.e., glucose oxidase, phenoloxidase, glutathione S-transferase, catalase activities, and vitellogenin contents) of house bees were preliminarily investigated. Oxalic acid contents of bee bodies and haemolymphs were also measured. The results confirm that oxalic acid is constitutively present in bee haemolymphs and its concentration is not affected by treatment. At 6 h after the treatment, a maximum peak of oxalic acid content was detected on bees’ bodies, which gradually decreased after that until physiological levels were reached at 48 h. In the immune system, the oxalic acid treatment determined a peak in glucose oxidase activity at 48 h, indicating a potential defence response and an increase in vitellogenin content at 24 h. No significant changes were recorded in phenoloxidase, glutathione S-transferase, and catalase activities. These results suggest a time-dependent response to oxalic acid, with potential immune system activation in treated bees.

Hydrolysable tannins are polyphenolic molecules contained in plant foodstuffs, potentially toxic for animals. Since tannins have been found in some bee products such as bee pollen, propolis, and honey, this work aimed to test the effects of tannins dietary assumption on bees' health. Results showed that supplementation of honey bees diets with 0.05% (w/w), as naturally amount reported in the honey, and 0.5% (w/w) of tannins significantly reduced bees' survival in a dose-dependent manner. In honey bees fed with a 0.5% tannins-enrichment diet a significantly decreased phenoloxidase activity than those fed with a 0.05% tannins-enrichment diet and with only syrup was recorded. Conversely, glucose oxidase activity significantly increased in honey bees fed with 0.5% tannins-enrichment diet than those with a 0.05% tannins-enrichment diet and only syrup. No differences were detected in glutathione S-transferase activity between honey bees fed with tannins-enrichment diets and syrup. Therefore, a naturally amount of hydrolysable tannins in foods can weakly affect bee wellness, whereas high levels of tannins can have a negative impact on honey bees' immunity and metabolism leading to a reduction of lifespan.

Background: Several studies investigated circulating levels of serotonin (5- HT) and brain-derived neurotrophic factor (BDNF) in children with Autism spectrum disorder (ASD). More limited literature focused on ASD adults or on populations with subthreshold autism spectrum manifestations, such as relatives of ASD probands. This study aimed to investigate 5-HT and BDNF levels in adults with autism spectrum conditions. Correlations between levels of biochemical variables and ASD symptoms were also evaluated. Methods: a sample of ASD adults, their first-degree relatives (Broad autism phenotype, BAP group), and controls were recruited and assessed with psychometric scales. Blood samples were collected from all participants. 5-HT and BDNF levels were measured by means of ELISA kits. Results: ASD adults showed significantly lower platelet-poor plasma (PPP) 5-HT levels than BAP and control groups. No significant difference was found among groups for PPP BDNF levels and intra-platelet 5-HT levels. 5-HT levels were reported to be specifically correlated with some autism symptoms. Conclusion: This work highlighted the presence in ASD adults of reduced PPP 5-HT levels than in other groups, without significant differences with respect to BDNF levels, supporting the hypothesis that biochemical correlates of ASD in adults may be different from those typically reported in children.

This study seeks to offer a contribution to the method of subtyping major depressed patients by exploring the possible relationships between circulating brain-derived neurotrophic factor (BDNF), different peripheral inflammatory/metabolic markers in the blood and clinical characteristics. Thirty-nine patients, thoroughly diagnosed according to the DSM-5 criteria, underwent a comprehensive set of evaluations encompassing structured interviews, rating scales and a panel of blood tests. Correlation and comparison analyses were carried out by means of non-parametric statistical tests. Concurrently, a principal component analysis was performed to explain biochemical variance. The findings of our research unveiled that leukocyte counts, their ratios and other inflammatory parameters are positively correlated with depression scores. Moreover, we found variations within the BDNF pools of depressed patients. Specifically, higher levels of platelet-poor plasma BDNF (PPP-BDNF) were correlated with augmented inflammatory markers in patients showing specific episode characteristics, whereas reduced platelet BDNF (PLT-BDNF) provided a better indication of the changes that were linked to a diagnosis of long-term depression. Our findings suggest that PPP-BDNF and PLT-BDNF might differentiate depression conditions. They also imply usefulness in appraising peripheral biomarker profiles in patients for a deeper characterization of major depressive episodes. At the same time, it is plausible that they might constitute novel avenues for developing more tailored therapeutic strategies for patients with MDs.

BackgroundThe importance of recognizing different kinds of autism spectrum presentations among adults, including subthreshold forms and the broad autism phenotype (BAP), has been increasingly highlighted in recent studies. Meanwhile, the possible involvement of immune system deregulation and altered methylation/trans-sulfuration processes in autism spectrum disorder (ASD) is gaining growing attention, but studies in this field are mainly focused on children. In this framework, the aim of this study was to compare plasmatic concentrations of IL-6 and homocysteine (HCY) among adults with ASD, their first-degree relatives, and healthy controls (CTLs), investigating also possible correlations with specific autism symptoms. MethodsPlasma concentrations of IL-6 and HCY were measured in a group of adult subjects with ASD, their first-degree relatives (BAP group), and healthy controls (CTL). All participants were also evaluated with psychometric instruments. ResultsIL-6 and HCY concentrations were significantly higher in the ASD group than in CTLs, while BAP subjects reported intermediate results. Significant correlations were reported between biochemical parameters and psychometric scales, particularly for the dimension of ruminative thinking. ConclusionsThese findings support the hypothesis of a key involvement of HCY-related metabolism and immune system alteration in autism spectrum pathophysiology. HCY and IL-6 seem to show different associations with specific autism dimensions.

Background Increasing literature highlighted alterations of tryptophan (TRP) metabolism and kynurenine (KYN) pathway in children with autism spectrum disorder (ASD). However, no study specifically focused on adult samples. Meanwhile, several authors stressed the relevance of investigating neurobiological correlates of adult forms of ASD and of those subthreshold ASD manifestations frequently found in relatives of ASD probands, known as broad autism phenotype (BAP). This work aimed to evaluate circulating levels of TRP and metabolites of KYN pathway in a sample of ASD adults, their first-degree relatives and controls (CTLs), investigating also the correlations between biochemical variables' levels and ASD symptoms. Methods A sample of ASD adults, together with a group of first-degree relatives (BAP group) and unrelated CTLs were assessed by means of psychometric scales. Circulating levels of TRP, KYN, quinolinic acid (QA), and kynurenic acid (KYNA) were assessed in all subjects. Results ASD patients reported significantly higher total scores than the other groups on all psychometric scales. BAP subjects scored significantly higher than CTLs. ASD patients reported significantly lower TRP levels than BAP and CTL groups. Moreover, significantly lower levels of KYNA were reported in both ASD and BAP groups than in CTLs. Specific patterns of associations were found between autism symptoms and biochemical variables. Conclusions Our findings confirm in adult samples the presence of altered TRP metabolism through KYN pathway. The intermediate alterations reported among relatives of ASD patients further stress the presence of a continuum between subthreshold and full-threshold ASD phenotypes also from a biochemical perspective.

Involving 1 million people a year, suicide represents one of the major topics of psychiatric research. Despite the focus in recent years on neurobiological underpinnings, understanding and predicting suicide remains a challenge. Many sociodemographical risk factors and prognostic markers have been proposed but they have poor predictive accuracy. Biomarkers can provide essential information acting as predictive indicators, providing proof of treatment response and proposing potential targets while offering more assurance than psychological measures. In this framework, the aim of this study is to open the way in this field and evaluate the correlation between blood levels of serotonin, brain derived neurotrophic factor, tryptophan and its metabolites, IL-6 and homocysteine levels and suicidality. Blood samples were taken from 24 adults with autism, their first-degree relatives, and 24 controls. Biochemical parameters were measured with enzyme-linked immunosorbent assays. Suicidality was measured through selected items of the MOODS-SR. Here we confirm the link between suicidality and autism and provide more evidence regarding the association of suicidality with increased homocysteine (0.278) and IL-6 (0.487) levels and decreased tryptophan (-0.132) and kynurenic acid (-0.253) ones. Our results suggest a possible transnosographic association between these biochemical parameters and increased suicide risk.

Converging, albeit scattered data mainly gathered in animals indicate that the neurotrophin brain-derived neurotrophic factor (BDNF) and the nonapeptide oxytocin (OT) interact in a cooperative way. Data in humans are really limited and indirect. Therefore, the aim of the present study was to explore the possible existence of a link between OT and BDNF in humans, by means of two peripheral markers, the platelet-poor-plasmatic-BDNF (PPP-BDNF) and the platelet BDNF (PLT-BDNF) and OT levels. Twenty-six young healthy controls of both sexes who volunteered for the study were included in the study. Fifty ml of peripheral venous blood were drawn from one-night fasting subjects between 8.00 and 9.00 a.m. The BDNF and OT assays were carried out according to common methods. Comparisons for continuous variables were performed by the Student's t-test for variables that follow a normal distribution, and by the Wilcoxon-Mann-Whitney test for variables not normally distributed. The correlations between biological markers were explored by calculating the Pearson's correlation coefficient or Spearman's rank correlation. The results showed that PLT-BDNF (pg/mg proteins, mean ± SD) and PPP-BDNF (pg/ml, mean ± SD) were 1546 ± 1844 and 10111 ± 1892, respectively. The OT levels (pg/ml, mean ± SD) were 13.92 ± 4.54. The OT levels were significantly higher in women than in men. The Spearman's analysis revealed a statistically significant and negative correlation between OT levels and PLT-BDNF (R = -0.543, p = 0.004). The findings of this study highlight the presence of a significant and negative correlation between OT and PLT-BDNF in a small group of healthy controls of both sexes. In any case, despite all the limits of peripheral biomarkers, they suggest that this reciprocal influence might have a downstream homeostatic function dampening one activity when the other is activated or no longer necessary, maybe at the level of the stress and/or immune systems.

Searching for artificial diets positively affecting the survival, immune and antioxidant systems of honey bees is one of main challenges occurring in beekeeping. Among nutrients, lipids play a significant role in insect nutrition as structural components in cell membranes, energy sources and reserves, and are involved in many physiological processes. In this context, the aim of this work was to investigate the effect of 0.5% and 1% coconut oil-enriched diet administration on newly emerged and forager bees survival rate, feed intake, immune system, antioxidant system and both fat and vitellogenin content. In newly emerged bees, supplementation with 1% coconut oil determined a decrease in feed consumption, an increase in survival rate from the 3rd to 14th day of feeding, a short-term decrease in phenoloxidase activity, an increase in body fat and no differences in vitellogenin content. Conversely, supplementation with 0.5% coconut oil determined an increase in survival rate from the 3rd to 15th day of feeding and an increase in fat content in the long term (i.e., 20 days). Regarding the forager bee diet, enrichment with 0.5% and 1% coconut oil only determined an increase in fat content. Therefore, supplementation with coconut oil in honey bee diets at low percentages (0.5 and 1%) determines fat gain. Further investigations to evaluate the use of such supplement foods to prevent the fat loss of weak families during winter are desirable.